Manufacture of azodyestuffs for dyeing cellulose esters



compound as stated Patented Apr. 30, 1929.

UNITED STATES PATENT OFFICE.

osm imncn'r, or BINNINGEN,

ITEAB BASED, SWITZERLAND, ASSIGNOB TO CHEE- IGAL WORKS FOBMERLY SANDOZ, OF

BASEL, SWITZERLAND.

MANUFACTURE OF vAZODYES'IT'III'FIES FOR DYEING CELLULOSE ESTERS.

Ho Drawing. Application filed December 23, 1925, Serial No. 77,880, and in Germany January 8, 1825.

Dyestuffs suitable for dyeing cellulose esters, 'which are too diflicultly soluble for practical application, have been employed, up to now, either in the form of their bisulphlte in the specifications of British Patent No. 204,280 (1923) or as N-alkyl-wsulphonic acids, according to the specifications of British Patent No. 197,809 (1923), No. 200,873 (1923) and No. 212,029 (1924). During the dyeing process the acld groups of these dyestuffs are split ofl' by hydrolysis, under the influence of the elevated temperature of the dye bath and the colors thus formed are then absorbed by the cellulose ester fibres.

It has now been found that it is possible to transform insoluble or difiicultly soluble azodyestuifs containing neither sulphonic nor carboxylic groups and possessing a particular aflinity for cellulose esters, into stable and soluble derivatives by introducing a radical of glycol into the molecule of the dyestufls in place of one or more hydrogen atoms of the aromatic nucleus. This can be erformed by coupling diazoarylglycolet ers which possess neither sulphonic nor carboxylic groups, but which may possess any other substituents, with azo components containing neither carboxylic nor sulphonic cups.

The dyestuffs thus obtained, apart from their good solubility, are distinguished by a articular aflim'ty for cellulose esters, so t at y their aid, bright and uniform shades may be obtained, without having to employ tem peratures, which would be injurious to the fibres. In those cases, where the dyestufis contain diazotizable aminogroups, the direct shades may be diazotized on the fibre and coupled with suitable developers.

The dyestufis obtained by the process as described above are entirely different from those referred to in the above mentioned patents the dyein with these last mentioned dyestufis is on y possible b the fact, that their acid groups, to which t eir solubiht in water is due, are split ofi by hydrolysis in ing the d cine process. In contrast to this, the glyoo -ra 'cals of the new dyestufis re- M main fixed to the dyestuft molecule during the dyeing process and their uniform dyeing and good penetration are rendered possible.

The following example illustrates the improved process.

Example.

19.8 kg. of glycol-2-amino-4-nitrophen 1- ether, obtained by partial reduction of g ycol-2.4-dinitrophenylether are dissolved in 100 litres of water and 24 kg. of concentrated hydrochloric acid, then diazotized at 0-5 C. with 6, 9 kg. of sodium nitrite and con led with 11 kg. of m-toluidine, whichhave en dissolved in 100 litres of water and 12 kg. of hydrochloric acid. The dyestufi precipitates in greenish brown crystals of bronzy brightness and is then filtered and dried; it forms a dark brown powder. Its hydrochloride dissolves in water, showing a yellow orange colour; this solution (1 es celluloseacetate in a yellow shade, whic by diazotizing and developing with ,B-naphthol is transformed into a brilliant red. The dyestufi possesses most probably the following formula:

oomcm-on om N=N NE:

The d estufl as developed on the fibre with fl-napht o1 possesses most probably the following formula:

oornornon N=N-QN=N H1 H0 N02 What I claim is:

lulose esters, obtained in coupling a diazo- 'tized aminoarylglycolether free from carboxylio. and sulphonic groups with an azo component also free from carboxylic and 5 sulphonio groups, said dyestuffs being in the form of the hydrochloride easily soluble in water and so dissolved dyeing 031- lulose esters of yellow to orange, red, brown, blue and violet tints, which diazotiz'ed and developed are orange, red, brown", blue, violet and black.

In Witness whereof I have hereunto signed my name this 10th day of December 1925. v OSKAR KNECHT. 

